Centrifugal yarn collection



Filed Nov. '7, 1962 INVENTOR CONRAD JOSEPH GONSALVES tframe into a sliver can or spinning pot.

United States Patent 3,187,496 r 1; CENTRIFUGAL YARN COLLECTION Conrad J. Gonsalves, Arnhem, Netherlands, assignor to American Enka Corporation, Enka, N.C., a corporation of Delaware I Filed Nov. 7, 1962, Ser. No. 236,094 Claims priority, a'pplicatizo p1 l fgetherlands, Nov. .24, 1961,

l his invention relates generally to. the centrifugal colrotating wall in .a direction toward the axis of rotation.

During such build up the spinning funnel is reciprocated axially of the rotating bucket to provide the proper layering. t

Yarn collecting means such as described above have a variety of uses, the most prevalent of which are found either in the initial collection of freshly spun viscose ray- 7 on or synthetic yarns, or in the spinning of fibers into yarn form, as by the guiding of a sliver from a drafting 'In the operation of either type apparatus described above, yarn passes axially through a hollow reciprocating funnel and is diverted 90 across the funnel end into the direction of the rotating spinning pot or bucket, Duryarn (filament or spun) collected in centrifugal pots frequently exhibit irregular twist. Moreover, it has been 'found that twist present in the yarn prior to passage across the funnel edge is lower than that which might be expected or that which is actually present after the yarn has been collected. This last-mentioned phenomenon is directly contrary to what one skilled in this art normally "would expect. The prior theory of operation has been that yarn passing across the funnel or stem edge spreads .intoa fiat ribbon which then slides around the stem edge during collection. It was expected, therefore, that the ribbon formation would displace yarn twist and that the amount of twist in the yarn prior to passage over the edge would be greater than in the yarn package. As indicated, however, experiments prove just the opposite results.

In view of the contradictory test results mentioned,

' additional study was directed toward the behavior of yarn passing over the stem edge of the funnel. This study tends to indicate that the yarn actually does not slide over the stem edge but in fact rolls or rotates irregularly and at varying degrees as it discharges from the funnel,

This being the case, the funnel edge eventually tends to function as a falsetwist device and imparts a tem porary twist to the yarn of an opposite hand or direcing passage, therefore, the yarn must slide longitudinally across the funnel end and must also'slide laterally around the end surface of the funnel to provide forproper package build up. In the normal operation, the rotating pack-. age or bucket" provides the necessary .force for feeding yarn. through the hollow funnel and across the funnel end Inasmuch as yarn fed in this mannerin eflectl is rotated about its own axis,a'certain amount of positive twist is imparted, the extent of which depends upon rela# tive yarn traveling speed and package rotation.

Conventional centrifugal yarn collecting means are known to have many disadvantages, particularly when used for collecting yarn having a low degree of twist. It has been found that in many instances filament breaks occur during collection of low twist yarn. The cause of tion to that of the final or positive twist. tion accounts for the fact that twist measured in the yarn prior to discharge from the funnel is lower than the final twist and the additional fact that the final, twist is distributed non-uniformly along the yarn length.

An object of the present invention therefore is to provide a centrifugal yarn" collecting apparatusnot having the disadvantages enumerated above.

.. Another object of this invention is to provide a centrifugally operated yarn collecting apparatus which functions to impart a uniform degree of twist to yarn processed thereby.

- Still anotherobject of the present invention is to provide a centrifugal yarn collector which will function to such breaks has beendifiicult to trace because 'the yarn was foundto have tensile properties corresponding very well to the tensile ,force of the spinning-pot. In other, words, the tensile properties approach or equal that which 1 might be expected from yarn collected by centrifugal means.

Breaks were particularly evident in the collection of yarn spun from fibers and passed through .a drafting frame into the centrifugal pot. It had previously been assumed that these breaks were introduced at the point where the spun yarn discharged from the drafting frame since there usually is very little fiber coherence and very little twist at this point in the process. Experiments have proved, however, that the same fiber breaks occur even if the drafting and collecting steps are practiced independently one of the other. It was also observed through high speed photography that only a minoramount of breaks occur when spun yarn is discharged from the drafting frame.

It has also been found through experimentation that eliminate or substantially reduce=yarn breaks previously produced. t i a l A further object of this invention is to provide a yarn collecting apparatus which may be operated at speeds higher than heretofore without encountering excessive yarn breaks or irregular yarn twist.

These" and other objects may beaccomplished in accordance with the present invention by providing a low frictional insert at the funnel edge to insure a true sliding contact between the yarn and funnel and to eliminate irregular 'yarn rotation heretofore encountered. While this insert may be formed entirely or partly from a polymer of a fluorine-containing ethene derivative such as perliuoropolypropylene, polytetrafluoroethylene, etc., an insert formed entirely from the latter material has proved most effective. t

It is conceivable that the object noted above could be accomplished by rotating the funnel or funnel stem at a speed corresponding to that of yarn entering the spinning pot. Such rotation of course would eliminate relative circular movement between the yarn and funnel edge with the result that only sliding movement of yarn radially across the funnel edge would occur. The funnel could either be driven or rotatably supported in suitable bearings for rotation due to contact with the rotating yarn. As indicated, rotation even: of the funnel edge only also would eliminate relative circular movement between yarn and a funnel.

. ally, complicated funnel supporting means must be pro- Patented June 8 1965 This assumpf vided 'at impractical expense. was abandoned.

Recourse was had to the publication Materials in De- Accordingly, this solution sign Engineering, 48 (1958), No. 4, pagesl06-l08,'

which describe the co-efficient of friction for polytetrafluoroethylene under various conditions. At sliding speeds of 300 f.p.m,, which correspond generally to yarn processing speeds of 100 meters per minute, no values lower than 0.22 were found for the frictional co'efiicien't between two sliding surfaces of this material. It may be assumed that the coefiicient of friction of either dry or wet spun yarn passing over a funnel edge at 100 me tersper minute will not be less than the above-mentioned value. Since a frictional coefiicient of 0.22 is certainly not unusually or exceptionally low, it is surprising that this material afforded such excellent results. 7

' For more details, attention is now directed to the single figure which illustrates in elevation the cross section of a centrifugally operated yarn collecting apparatus.

A spinning pot or bucket 1 of conventional configuration is provided for collecting a cake or package of yarn 2. Hub 3 is rigidly secured coaxially to the bottom of spinning pot 1 and serves to support the pot on spindle 4. In the apparatus shown, spindle 4 may be freely rotatably supported on'bearings (not shown) and a drive belt 5 may impart rotation to the pot, hub and spindle. Other arrangements of course arepossible and, if desired, spindle 4 could be used for imparting rotation to the pot.

A tubular spinning funnel 6 projects into the'spinning pot and is aligned axial-1y with the pot cake and spindle. The funnel may be supported and reciprocated vertically by conventional'm'eans (not shown). As is known in this art, yarn 9 (which may be freshly spun continuous artificial filaments or a natural fiber such aswool, cotton,

etc.) is fed from a supply source through the tubular funnel and is urged outwardly toward cakelZ by centrifugal force generated through rotation of'the spinning I pot. Axial reciprocation of the funnel provides the necessary traverse function for package build up.

A cap 7 normally is attached to the discharge end of funnel 6 in order to restrict passage of yarn outwardly and eliminate sloughing of yarn over the package ends during reversal oftraverse strokes. This cap hereto fore has also provided the contact surface between yarn 9 and funnel 6. I

' The present invention contemplates the addition of an insert 8 formed partly or entirely from a polymer of fluorine-containing ethene derivative such as polytetrafluoroethylene. This insert is ring-shaped to form an annular rim projecting above the outer-surface of cap 7 and may be attached or clamped to the cap in any de' sirable manner.

Asshown, a recess has been formed in the cap to receive insert 8, and the insert may be maintained in position'byadhesive or other means.

"-It has been found through operation of the apparatus described above that rolling of yarn across the contact surface of the funnel edgehas been substantially reduced,

false twist and erratic fiber breaks have also been substantially overcome. In addition, it has now been found that the operating speed of this. type apparatus may be increased substantially, since the amount of twist to be imparted to spun yarn may now be smaller, resulting in an increased drafting frame speed while maintaining the normal spinning pot speed. s

Inasmuch as other modifications will become apparent to thoseskilled'in the art, it is. intended that the present invention be limited only to the extent set forth in the following claims.

What is claimed is:

1. In a centrifugally operated yarn collection means utilizing a rotatable spinning pot and an axially reciprocated spinning funnel, having a lower edge in contact with yarn during collection, the improvement comprising an insert added to the lower edge of the spinning funnel in contact with the yarn, said insert being formed at least partly from a polymer of a fluorine-containing ethene derivative.

2; A centrifugally operated yarn collecting apparatus stantially from polytetrafluoroethylene.

'4. A yarn collecting assembly comprising a spinning bucket mounted for rotation about a vertical axis, means for rotating said spinning bucket, a tubular spinning fun nel supported axially of said bucket and having a discharge end mounted for vertical reciprocation within saidtbucket, an apertured cap secured to the discharge end of 'said funnel for'restricting the longitudinal opening therein, and an annular insert formed from polytetrafluoroe'thylene secured to the cap coaxially about the aperture thereof for providing a contact surface having -a low coefiicien't of friction, for receiving yarn fed through said tubular funnel fand 'for deflecting the same about said discharge end for collection within said spinning bucket.

References Cited by the Examiner UNITED STATES PATENTS 2,320,590 6/43 Haley 5776 2,411,049 ll/46 Madden 57-76 2,633,693 4/53 Bolton et-al. 57-76 2,831,313 4/58 Burns et al 28-1 MERVIN STEIN, Primary Examiner. 

1. IN A CENTRIFUGALLY OPERATED YARN COLLECTION MEANS UTILIZING A ROTATABLE SPINNING POT AND AN AXIALLY RECIPROCATED SPINNING FUNNEL, HAVING A LOWER EDGE IN CONTACT WITH YARN DURING COLLECTION, THE IMPROVEMENT COMPRISING AN INSERT ADDED TO THE LOWER EDGE OF THE SPINNING FUNNEL IN CONTACT WITH THE YARN, SAID INSERT BEING FORMED 